     program demo_change

      use M_strings, only : change
      implicit none
      character(len=132) :: line='This is a test string to change'
      integer            :: ierr
         write(*,*)trim(line)
         ! change miniscule a to uppercase A
         call change(line,'c/a/A/',ierr)
         write(*,*)trim(line)
         ! put string at beginning of line
         call change(line,'c//prefix: /',ierr)
         write(*,*)trim(line)
         ! remove blanks
         call change(line,'c/ //',ierr)
         write(*,*)trim(line)
  end program demo_change
